Helium Leak Test & Ammonia Leak Tests are two different Tests for sensitive leakage detection. We are thinking of using a mixture of both gases to save time. As recommended soaking time in case of Ammonia is 08 hours and that four Helium is 01 hour. So by mixing the two gases we can attempt Helium Leak test during soaking time of Ammonia. If some one has any expiernec or any apprehensions kindly please share.

08:50 May-12-2008 Re: Helium-Ammonia mixture for leak test Which type of tests you need? what is admitted leak value and pressure? It is a Bombing Test?In any case, please consider that ammonia can damage helium leak detector, expecially if you utilise it in Vacuum Mode. Ammonia soak during helium test can change the helium signal.Please send me further information if you need assistance.

----------- Start Original Message -----------: Helium Leak Test & Ammonia Leak Tests are two different Tests for sensitive leakage detection. We are thinking of using a mixture of both gases to save time. As recommended soaking time in case of Ammonia is 08 hours and that four Helium is 01 hour. So by mixing the two gases we can attempt Helium Leak test during soaking time of Ammonia. If some one has any expiernec or any apprehensions kindly please share.------------ End Original Message ------------

02:11 May-13-2008 Re: Helium-Ammonia mixture for leak test Thanks for your reply. We are experiencing a very minute leakage in our Urea Stripper (carbamate on Tube side & steam on shell side). Here are the details of the two leakage tests we can perform separately.

A mixture of Nitrogen & 15% by volume of Ammonia is used to pressurize the shell side. A soaking time of approx 8 hours is required. Nitrogen is used to increase the pressure & thus increasing the sensitivity.

A mixture of Helium & Nitrogen is used to pressurize the shell. The soaking time is 1 hour. Nitrogen is used to increase the pressure & thus increasing the sensitivity.

Now to save time, why not use a mixture of helium & ammonia to pressurize theshell side. This way after 1 hour of Helium soaking we would be able to start performing Helium Leak Test and by the time we would complete our helium leak test hopefully soaking time of ammonia (i.e 8 hours) would be over and we would apply ammonia sensitive paper on both tube sheets.

As helium test is not recommended in moist environments. The molecule of Ammonia & that of water are similar in terms of hydrogen bonding. So one of our apprehension is that would ammonia gas would behave like moisture and adversely effect the sensitivity of helium leak test.

More details can also be provided. we would definetly love to have your assistance. Helium Leak tester being used by us is MKS sniffer method using mass spectropetry.

From considerations of sensitivity, Helium is the first choice, because of two reasons:

Firstly, Helium is much lighter than nitrogen and hence diffusion rates through the leak are faster.

Secondly, the helium content in the atmosphere is very less and so the background effect is much less.

Nitrogen has been used in the leak testing in some special cases. If your needs of sensitivity are met with nitrogen based leak testing equipment, the economies could be an important factor in your choice of the medium.

Pls suggest: (helium Leak test)
What is the time of soaking in pressurizing method (Shell side 10% He +Nitrogen) Pressure 1kg/Cm2.
Volume of shell side is Approx- 2.341E+08
cm3 & Tube side will be enveloped in sex sector (Volume of tube side: 2.806E+08 Cm3)
How to calculate?

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